1. Field of the Invention
This invention relates to a new and improved electron-beam heated source for use in a high vacuum environment to make high grade thin film coatings and the like. More particularly, the invention relates to apparatus employing a water cooled crucible in which the substance which is to be evaporated to make the film coating is placed. An electron- beam gun is positioned on one side of the crucible in such position that the evaporated substance does not damage the gun. In order to direct the path of the electrons emitted from the gun to the crucible, a plurality of magnets is disposed on opposite sides of the crucible to create a transverse magnetic field extending over the top of the gun and the substance to be evaporated. The positioning of such magnets guides and focuses the electrons in a convex path upward and then down into the substance. The magnets may be either permanent or electro- or a combination thereof.
2. Description of Related Art
Prior equipment of this general nature has employed horizontal magnets and utilizes the leakage field around the magnet, guided by pole pieces to provide the required field. Only about one-quarter of the magnetic flux generated by this magnetic arrangement is usefully employed and the rest is lost in leakage flux around the remaining three-quarters of the perimeter of the magnet core not covered by the poles. The present invention is an improvement upon existing art.